as far as I remember, didn’t double check, the 2GB per buffer is a scintilla limit.
But I might be wrong or “outdated”, so, anyone (or everyone), correct me if I’m wrong.

And just to alleviate the concerns for those who think that, because of that limit,
x64 doesn’t provide advantage over x86, this is false. Remember an x86 application
can only address 2GB memory (well it can address 4 but 2 are reserved for system),
which means if it has loaded a file which already exceeds this limit it can’t open
any further, whereas the x64 npp version can now, in theory, have multiple 2 GB files open. Why “in theory”, because I don’t know if anyone has already tested if this is the
case and you need to have the amount of ram available and …

These kinds of comments concern me because lots of users think that once N++ can open “huge” files that it will work fine. There are several operations N++ does that are a huge performance hit if the file is large. Some can be disabled (auto-completion, backups, etc) while others can’t. Not to mention if additional plugins are installed.

I agree strongly with @dail 's comments. The 64-bit version of Notepad++ is something that simply must be done as a matter of evolution, not something that (for me and likely a lot of others) is currently all that useful. At the moment, there is very little to be gained by using the 64-bit version, and a lot to lose (most plugins are not available in 64-bit form, and the potential issues dail points out). These things will change with time, and of course the developers extending the code to 64-bit is the right move. For users (especially non-newbies), the choice is currently not so clear…